Problem: $72$ is what percent of $200$ ?
Explanation: Having a percent of something means that you get that percent out of every $100$ We can set up a proportion to find out what percent of $200$ we need to take to get $72$ $ \dfrac{{\text{percent}}}{100} = \dfrac{{\text{part}}}{{\text{whole}}}$ Which things do we know, and what are we trying to find? We are trying to find the ${\text{percent}}$ . Is $200$ the ${\text{part}}$ or the ${\text{whole}}$ The $200$ is the ${\text{whole}}$ . This means the ${\text{part}}$ is $72$ $ \dfrac{{\text{percent}}}{100} = \dfrac{{72}}{{200}}$ If we divide the denominator of the fraction on the right by $2$ , it will be the same denominator of the fraction on the left. To keep things equal, let's also divide the numerator on the right by $2$ $ \dfrac{{\text{percent}}}{100 } = \dfrac{{72 \div 2}}{{200 \div 2}}$ $ \dfrac{{\text{percent}}}{100 } = \dfrac{{36}}{{100}}$ $ {\text{percent}} = {36}$ So $72$ is $36\%$ of $200$.